Specify your lemma list in the main Controller.

 

In the following case a lemma list was used and lemma search specified, with a concordance on the word abandon:

 

with these results showing which form of the lemma was used in the Set column.

 

In the collocate window below, the red line in row 1 indicates that the 140 cases of ABANDON include other forms such as 78 cases of ABANDONED and 19 of ABANDONING (greyed out below).

 

The red mark by BE (row 5) shows that this row gives collocation numbers covering all forms of BE such as WAS, WERE etc. Similarly, HAVE and A are lemmatised in this screenshot.

Thus, for your search-word and its variants you can see detailed frequencies. To see the various lemma forms, choose View | Show joined items.