The WTS does put restrictions on how anniversaries SHOULD be observed. I can remember a couple that celebrated their 25th anniversary before the days when LARGE events were frowned on. They had over 300 people there. Twenty-five years later for their 50th, although the size restrictions were in place, they still had a large event (200 people). BTW, the WTS has never defined how to determine how many people would constitute a LARGE event.
*** w98 10/15 p. 30 Questions From Readers ***It thus would not be strange that a couple might on their wedding anniversary take time to reflect on the joyfulness of that event and on their resolve to work for success as a couple. Whether they focus on this happy occasion in private, just as a couple, or they have a few relatives or close friends with them would be for them to decide. The occasion should not become a mere excuse for a large social gathering. On this occasion Christians would want to be guided by the principles that apply every day of their lives. So whether one takes note of a wedding anniversary or not is a personal matter.
*** w71 12/1 pp. 735-736 Questions From Readers ***Other couples may find pleasure in sharing the happiness of their anniversary with a few Christian friends and relatives, including their children. If this is done, there are certain balancing cautions that ought to be kept in mind.
With any social gathering or celebration, care has to be exercised that things do not get out of hand. Even a modest celebration can become uncontrolled or can lead to improper conduct, as appears to have occurred sometimes among the Jews in the first century. (John 2:10) That unquestionably would be wrong for Christians. (1 Pet. 4:3, 4) Nor would it be fitting for celebrants to give humans excessive honor, as if the couple whose anniversary it is ought to be venerated. The Bible clearly shows that veneration should go to the Creator, not to any created thing on earth, whether animal or human. (Rom. 1:24, 25) If a couple have had a successful marriage, that is fine. Others can rightly be happy for them. But should not this also stimulate thankful praise to the Author of marriage? He should be kept in mind and all that is done should bring honor to Him.
In making the above comments we are not recommending to couples who do not have this custom that they now begin to celebrate their wedding anniversary. Actually, we are neither encouraging nor discouraging wedding anniversaries