The ornamental design for a footwearlastextension, as shown and described.
FIG. 1 is a front, top, right isometric view of a footwear last extension showing our new design;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a front view thereof; and,
FIG. 7 is a rear view thereof.
The broken lines immediately adjacent to the shaded area represent unclaimed boundaries of the design. The unshaded regions form no part of the claimed design. The broken lines showing the remainder of the footwear last extension are provided for environmental purposes only and form no part of the claimed design.